1. Field of the Invention
The present invention relates to an image formation apparatus which performs image formation, with a cartridge mounted therein.
2. Related Background Art
Conventionally, it has been known a color image formation apparatus in which plural image stations respectively corresponding to plural toner colors are arranged side by side.
In such the color image formation apparatus, even if a density of one of plural kinds of toners changes, a tint of an image obtained after multitransfer is performed is remarkably different from that of an original image, so that color reproducibility deteriorates. Therefore, in order to prevent such inconvenience, it is necessary to always maintain the toner density at a constant level. For this reason, for example, a ratio of the toner to a carrier (i.e., magnetic substance) in a development unit is measured by a sensor, and an obtained value is controlled to be close to a target density value. In this case, such a sensor output value differs according to an individual difference of each sensor and an environment in which the apparatus is being placed. Thus, it is necessary to previously read the sensor density of each image station at a time when the apparatus is initially placed, and store the read density in a memory of a body of the apparatus as the target density value.
Since such the color image formation apparatus is expensive and also difficult to be adjusted, it has been expected in recent years to downsize the apparatus, decrease a cost by reducing the number of parts, and simplify the adjustment. As the apparatuses capable of meeting such expectation, there have been known a copy machine, a printer and a facsimile apparatus each containing, in the form of a cartridge, an image formation station into which a photosensitive drum and a development unit to form a latent image are integrated. Further, it has been proposed to provide a memory in the cartridge and thus previously store an appropriate image formation condition in this memory.
Although such the image formation apparatus containing the cartridge of the image formation station into which the photosensitive drum and the development unit to form the latent image are integrated has the merit that a user can easily exchange the cartridge, there is some fear that the user erroneously mounts the cartridge currently used for one apparatus in the other apparatus.
By such an erroneous operation, the target value for maintaining the constant density in the development unit of one cartridge is controlled based on a target value of the other cartridge, so that it becomes impossible to correctly control the toner density of the development unit, thereby occurring a problem that color reproducibility of an original image is deteriorated.
Further, in a case where data representing the appropriate image formation condition is separately stored in both the memory of the image formation apparatus and the memory of the cartridge, the correct image formation condition data can not be obtained if a different cartridge is mounted.
An object of the present invention is to provide an image formation apparatus and its control method which eliminated such drawbacks as described above.
Another object of the present invention is to provide a cartridge, an image formation apparatus and its control method in which the cartridge is caused not to be used in apparatuses other than the specific apparatus to prevent image formation in inappropriate image quality.
Still another object of the present invention is to provide a cartridge, an image formation apparatus and its control method in which the apparatus corresponds to the cartridge one-to-one to allow high-quality image formation.
Other objects of the present invention will become apparent from the following detailed description based on the accompanying drawings and the claims.